Skip to main content

About your Search

20121001
20121031
Search Results 0 to 0 of about 1
and civilization. many of the world's great cities were first established as riverside settlements, and throughout their history these cities have depended on the river for food, a water supply, and an avenue of transport and trade. but like all natural systems, rivers undergo relatively rare but extreme events. river flooding is a threat to nearly every nation on earth. in the united states, floods exact the greatest toll of any geologic hazard, causing billions of dollars in property damage and killing about 100 people every year. and this loss is modest when compared to the destruction in countries with primitive flood control systems, or the devastation in preindustrial societies which were visited by floods without warning. like most natural systems, rivers change and evolve through time in response to a variety of geologic factors that are themselves changing. factors such as regional climate, hill slope, tectonic activity, vegetation, and the bedrock composition of the earth's crust. so the behavior of rivers is controlled by physical laws and geologic processes that can be observed and und
Search Results 0 to 0 of about 1